Bar code scanning comprises the generation of a scan pattern to illuminate a bar code so as to scatter light from the bar code, to use this scattered light to generate a scan signal, and to process the scan signal to decode the bar code so as to extract encoded information. The encoded information is provided to a host device. Numerous formats are used for bar codes, with a scanner typically identifying the bar code format of a detected bar code to the host device.
An organization implementing a bar code system may sometimes wish to replace the bar codes used for one purpose with bar codes of another format. Organizations, such as retailers, may use a particular bar code format for designated purposes, such as prescriptions or customer loyalty cards. A retailer may be using a nonomnidirectional bar code format, such as Code 39, Code 128, or code interleaved Two of Five, for a designated purpose, and may wish to begin using a more convenient bar code format for that purpose. For example, a retailer may be reading a nonomnidirectional bar code on omnidirectional scanners, and may wish to change to an omnidirectional bar code in order to avoid inefficiencies and difficulties that may accompany reading of nonomnidirectional bar codes on omnidirectional scanners. Such difficulties include poor scan angles provided by the bar codes, or bar code lines too short for efficient reading by omnidirectional scanners.
However, a host system to which bar code information is provided by a scanner, such as a point of sale system, receives and uses bar code format information in order to interpret the bar code. If a new format is introduced for the same purpose, two different formats will be used, and will need to be interpreted by host systems, until all the previously existing bar codes are purged out of the system, for example, until all goods bearing the previously used bar codes are sold or otherwise disposed of, or until all customer loyalty cards bearing the previously used bar codes are replaced. Such purging may take months or years, depending on the uses to which the bar codes are being put, and during that time, the host system will need to accommodate two different formats of bar code, the previously existing format, and the newly introduced format.